The invention relates to an apparatus for transmitting signals between a rotating and a stationary part.
An apparatus of this kind is desirable for example in an x-ray examination device in which case the patient is scanned by means of a measuring arrangement consisting of an x-ray tube and a radiation detector at different projections and the attenuation coefficients of the examined layer of the patient are determined from the output signals of the detector. In a computer-tomograph of this kind, the examination time is determined essentially by the scanning time of the measuring arrangement. It is known to revolve the measuring arrangement by an angle of 360.degree. around the patient for a scanning procedure and subsequently to return it to its starting position for the next scanning procedure. In this case the detector can be connected to the electronics which process the measured values by way of cables. However the times required for accelerating the measuring arrangement limit the scanning time. It would be possible to shorten the scanning time if the measuring arrangement were to rotate continuously. In this case cables would no longer have to be used for the x-ray tube or the detector for the purpose of supplying current or removing signals respectively. The supply to the x-ray tube can take place for example by way of slip rings. However in this case neither slip rings nor inductive transformers can be considered for detecting the signals of the detector because of the high data rate and the requisite freedom from interference. In order to economize on the expensive temporary memory on the rotating part, the data transmission must take place at least exactly as quickly as the data collection. Hence very high speeds of approximately one to thirty megabits per second (1 to 30 mbit/sec) are suitable.